1. Field of the Invention
The present invention relates to a heat exchanger having an adsorbing core and a method of manufacturing such a core.
2. Description of Related Art
Recently, technologies for collecting or recuperating exhausted heat are becoming important. In particular, a technology for collecting heat that is generated in a high volume at a relatively low temperature lower than 100 degrees is urged to be established. An adsorbing type refrigerator is one of the important devices for collecting exhausted heat. However, there is a problem that the heat exchanger of this type is large in size because an adsorbing core requires a large space. Accordingly, it is highly desirable to provide a technology for reducing the size of the adsorbing core.
Quick release of the heat generated by attracting fluid greatly contributes to reduction of the size of the heat exchanger. Attracting ability of attractants Q(W) is expressed in the following formula: Q(W)=V×W×L, where V (g/g·s) is attracting velocity, W (g) is weight of the attractants, and L (J/g) is latent heat of fluid to be attracted. As clear from this formula, a desired amount of the attractant ability Q can be attained by increasing the attracting velocity without increasing an amount of attractants. This means that if the heat generated on the attractants is quickly dissipated, the attracting velocity can be increased. To increase the heat dissipation speed, the attractants have to be closely connected to an outer surface of a heat exchanger. In other words, a contacting heat resistance between the attractants and the heat exchanger has to be reduced.
An example of a method for firmly connecting attractants to a surface of a heat exchanger is disclosed in JP-A-2005-111425. In this method, the outer surface of the heat exchanger is made rough before the attractants are attached. Seed crystals of the attractants are attached to the rough surface, and then the attractants are grown on the seed crystals by a hydrothermal crystal growth method.
In this method, however, the seed crystals are simply attached to the rough surface without holding them thereon. Accordingly, the seed crystals cannot be held on the surface with a sufficiently high connecting force though a contacting area of the surface is increased by making the surface rough. There is a possibility that the seed crystals may drop off from the surface. When the surface of the heat exchanger on which the seed crystals are attached is dipped in a solution for growing crystals in the hydrothermal crystal growth method, the seed crystals may drop off from the surface. At a portion of the surface where the seed crystals dropped off, the attractant crystals cannot be grown properly. Therefore, an effective area of the attractant layer becomes narrow, and it is difficult to make the heat exchanger compact.